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Math Help - roots and radicals

  1. #1
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    roots and radicals

    Solve each equation. Round your answer to two places if necessary.
    26. 1875=3a^4

    32. 10.56=12.4(1-r)^20

    i don't understand this two problems. the two problems are color colded.
    i hope it is ok to post this two problems in this thread. if not, sorry.
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  2. #2
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    Quote Originally Posted by comet2000 View Post
    Solve each equation. Round your answer to two places if necessary.
    26. 1875=3a^4

    32. 10.56=12.4(1-r)^20

    i don't understand this two problems. the two problems are color colded.
    i hope it is ok to post this two problems in this thread. if not, sorry.
    1.
    1875 = 3a^4
    Divide both sides by 3:
    625 = a^4
    Do forth root on both sides:
    \sqrt[4] {625} = \sqrt[4] {a^4}
    5 = a

    2.
    10.56 = 12.4(1-r)^{20}
    Divide both sides by 12.4:
    0.8516... = (1-r)^{20}
    Do twenty root on both sides:
    \sqrt[20] {0.8516...} = \sqrt[20] {(1-r)^{20}}
    0.992... = 1-r
    Add r to both sides:
    0.992... + r= 1
    Take 0.992... away from both sides:
    r \approx 0.007999
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